Motor Braking Circuit for Rapid Robot Stops Under Power Loss
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Solution Overview
Problem
Autonomous mobile devices, such as robots, face challenges in performing safe and controlled rapid stops, especially in scenarios involving partial or complete power loss, which can lead to skidding or component damage.
Innovation Solution
A braking system that includes a motor cutoff circuit, a braking circuit, and a stop circuit, which disconnects power to the motor, dissipates energy through resistors, and shorts the motor terminals to prevent further rotation, ensuring a controlled deceleration and safe stop, even in the event of power failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the motor is disconnected from power during rapid braking, then the robot can stop more quickly, but the motor may generate back-EMF that causes uncontrolled rotation or component damage
Solution Approach 1:
A diode is introduced as an intermediary component between the motor and power source. The diode allows controlled current flow during back-EMF generation, preventing uncontrolled rotation while dissipating energy safely. This intermediary component resolves the contradiction by enabling rapid deceleration without compromising component safety.
Solution Approach 2:
The back-EMF, which was previously a harmful effect causing uncontrolled rotation, is converted into a beneficial braking force. By allowing the motor to generate back-EMF in a controlled manner through the diode, the system utilizes this electromagnetic effect to assist in rapid deceleration, transforming a potential hazard into a useful function.
2Stability of the object's composition
If the braking circuit dissipates energy through resistors, then the robot achieves controlled deceleration, but energy is lost as heat
Solution Approach 1:
The kinetic energy that would otherwise be wasted as heat during braking is converted into electrical energy through back-EMF generation. This electrical energy is then stored in the capacitor, transforming the harmful energy dissipation into a useful energy storage mechanism that can be reused.
Solution Approach 2:
Instead of discarding the kinetic energy through resistor dissipation, the system recovers this energy by converting it to electrical form via back-EMF and storing it in the capacitor. This recovered energy can be reused for subsequent operations, reducing overall energy consumption.
3Reliability
If the system uses a complex braking circuit with multiple components, then braking reliability improves, but device complexity increases
Solution Approach 1:
The motor serves multiple functions: it acts as both a drive motor during normal operation and as a generator during braking through back-EMF. The capacitor also serves dual purposes by storing energy during braking and providing power during startup. This multi-functionality reduces the need for separate dedicated components, simplifying the overall system.
Solution Approach 2:
The braking function is merged with the existing motor and power management components rather than adding a completely separate braking system. The diode and capacitor are integrated into the existing circuit architecture, combining multiple functions (braking, energy recovery, power management) into a unified system that achieves high reliability without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables the robot to perform rapid stops safely and predictably, reducing the risk of skidding or component damage, with low latency and reliability, even under partial or complete power loss conditions.
Implementation Method 1
a braking circuit to dissipate the power produced by motion of the motor
Implementation Method 2
the back-EMF produced by the motor falls below a threshold value
Data Source
AI summary
A device that uses a motor may quickly and safely stop the motor using a rapid braking system. For example, the device may stop to avoid collision with an object, upon determining a failure of an internal component, upon receipt of a command, and so forth. Responsive to a signal to stop, the motor is disconnected from the battery. A braking circuit is activated that dissipates, in a controlled fashion, power produced by continuing motion of the motor. When the voltage produced by the motor's continuing motion drops below a threshold, a stop circuit shorts the terminals of the motor, causing the motor to resist further rotation. When the stop condition no longer applies the signal to stop is removed resulting in the motor being reconnected to the battery, the braking circuit being deactivated, the stop circuit opens the short between the terminals of the motor, and normal operation resumes.